Such a circuit breaker is known, in particular from European patent application EP 0 313 813 published on May 3, 1989. The first main contact and the first arcing contact are secured to a first rack which co-operates with a pinion mounted in a fixed position in the circuit breaker and rotatable about an axis that is perpendicular to the common axis. The second arcing contact is formed by a rod in which a second rack is inserted that meshes with the pinion at a contact point that is diametrically opposite its contact point with the first rack.
During opening of the circuit breaker, conventional control means drive the first main contact and the first arcing contact along the common axis in a direction such that the first main contact separates from the second main contact which is stationary in the circuit breaker. The second arcing contact is simultaneously displaced in the opposite direction by means of the two racks and the pinion, so as to be separated from the first arcing contact. Provision is also made to double up the pinion and the above two racks, placing them on both aides of the common axis so as to balance the transmission forces applied to said elements when opening the circuit breaker.
The pinions and the racks that enable displacement to be transmitted to the second arcing contact in a direction that is opposite to the displacement of the first main contact and the first arcing contact are disposed inside the second main contact which is cylindrical, and they give rise to a problem of bulk. The use of pinions and racks has also turned out to be relatively expensive, given the need to make the gear teeth of those elements.